The Vitamin D Dose Response in Obesity.

Objective: Prevalence of vitamin D inadequacy is high in obese individuals. Determining the response of serum 25-hydroxyvitamin D [25(OH)D] to vitamin D3 supplementation in obese and non-obese individuals may lead to concurrent recommendations for optimal vitamin D intake in these populations. The objective of this study was to determine the dose response of vitamin D3 in subjects with body mass index ≥ 35 kg/m2.

Design and Methods: Randomized, double-blind, placebo-controlled study. This study is an extension of our previous study of vitamin D dosing in healthy adults. After an assessment of baseline 25(OH)D levels, participants were randomized to a vitamin D supplementation arm (100 μg daily if baseline 25(OH)D was < 50 nmol/L, or 50 μg daily if baseline 25(OH)D was ≥ 50 nmol/L) or placebo arm.
Subjects with baseline 25(OH)D level ≥ 80 nmol/L were excluded from the study. Two months following randomization, a repeat 25(OH)D measurement was done.